Include "Main" an install target category.

xtrn/hamtest/install-xtrn.ini

 Name: HAM Test
 Desc: Amateur radio operator license exam practice tests
 By:   Deuce (Stephen Hurd)
-Cats: Tests
+Cats: Tests, Main
 Subs: Radio, HAM, JavaScript
-Inst: $Id: install-xtrn.ini,v 1.2 2020/04/17 08:27:36 rswindell Exp $
+Inst: 2020/09/16
 
 [prog:HAMTEST]
 cmd  = ?hamtest.js